In recent years, Rankine cycle type power generation systems have been considered as power generation systems that perform power generation, using exhaust heat from vessels, factories, gas turbines, or the like, the heat of the earth, solar heat, temperature difference between cooler deep and warmer shallow ocean waters, and the like as heat sources, from viewpoints of effective energy use, environmental preservation, or the like (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2006-299996; Japanese Unexamined Patent Application, First Publication No. 2006-313048; and Japanese Unexamined Patent Application, First Publication No. 2006-313049). In this case, when the heat sources as described above are used, for example, organic fluids that are media (for example, chlorofluorocarbon media or the like) having a boiling point lower than that of water are used.
In such power generation systems, as shown in FIG. 4, a medium circulates within a cycle circuit 5 having a preheater 1, an evaporator 2, a turbine 3, and a condenser 4, using a circulation pump 6.
A heat medium that has recovered heat from the heat sources as described above is sent into the evaporator 2, is made to perform heat exchange with the medium, and evaporates and gasifies the medium. Additionally, the heat medium that has passed through the evaporator 2 preheats the medium in the preheater 1 provided in the preceding stage of the evaporator 2.
The gasified medium expands in the turbine 3, thereby rotationally driving a main shaft 3a and driving a generator 7. The medium that has expanded in the turbine 3 is condensed in the condenser 4 and returns to the circulation pump 6.
An alternating current (AC) output as the generator 7 is driven is converted into a direct current (DC) in a rectifier 9, and the converted direct current is re-converted into an alternating current in a system interconnection inverter 10 and is output to the outside as generated electric power.